SNMP auto LVS balancing Jason Liptak

Overview SNMP overview Network Setup Solution Lessons Learned Future 5/4/2011Jason Liptak 2

SNMP – purpose Monitor Network ▫Servers, Switches, Printers, etc. Change network remotely Community strings to access ▫Public / Private ▫Plain text Version 3 ▫Added security 5/4/2011Jason Liptak 3

SNMP - Implementation Agents running on devices to respond Management information base (MIBs) ▫Describe structure layout of information ▫Tree layout via numbers specify object identifiers (OID) Messages ▫Get(Request/NextRequest/BulkRequest) ▫SetRequest ▫Response 5/4/2011Jason Liptak 4

Goal Using SNMP information ▫Change load balance of LVS ▫Preemptive load balancing ▫Extendable design to other MIBs 5/4/2011Jason Liptak 5

LVS -Access to internet -Access to local -Polls SNMP Server 2 -Access to local -Running SNMP -Running Web Service Server 1 -Access to local -Running SNMP -Running Web Service 5/4/2011Jason Liptak 6

Solution - Scripts Schedule balance script to run ▫“at –f script now+1min” Python script to monitor and modify ▫Change ipvsadm ▫Poll SNMP ▫Parse SNMP SNMP parsing method ▫Dictionary tree 5/4/2011Jason Liptak 7

Solution - Calculation Processor usage determines load ▫Large requests going to one server ▫Remotely accessing one server ▫Processor not running efficiently Simple calculation ▫(100 – processor usage) Sample calculation, easy to change via scripts 5/4/2011Jason Liptak 8

Lessons Learned Needed better SNMP parsing ▫More efficient structure and parsing ▫Ability to aggregate OID sections SNMP overhead ▫Specific subsections have unneeded information 5/4/2011Jason Liptak 9

Future Calculations on more SNMP data ▫Memory ▫Interface speed ▫Processes See SNMP overhead ▫Depends on targeted OIDs Real test ▫Put in real world work loads and set up 5/4/2011Jason Liptak 10